Axial Load Effects on the Response of Yielding Links in Eccentrically Braced Frames

Previous studies have shown that yielding links in eccentrically braced frames (EBFs) may be subjected to axial loads during their response. Axial tension increases the strength of yielding links, while axial compression reduces their shear force capacity. This paper provides a brief review of past research on EBFs and different types of commonly used yielding links in EBFs. The mechanisms through which axial loads are imposed on yielding links in EBFs are discussed. A set of simplified equations based on the mechanics of the yielding links are proposed for predicting the increase or decrease in the link's shear force under axial loads. Comparison between results from the proposed equations with past experimental results and results from additional finite element analyses (FEAs) demonstrate the enhanced accuracy of the proposed equations. The effects of axial loads on the ultra-low-cycle fatigue life of yielding links are also discussed. Lastly, the effects of axial loads in yielding links on the global response of EBFs is presented. In the end, a set of guidelines is provided for considering the effects of axial loads on yielding links in the design of EBFs.